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At a conventional junction, pedestrians are separated from motor vehicles, while cyclists are placed in the [[carriageway]] with motorists. Cycle lanes are often placed on the nearside (right in [[right-side driving countries]]; left in left-side countries) of the carriageway, which can create conflict, for example when a cyclist is going straight ahead and a motorist is turning to the nearside.<ref name="Butler" />
At a protected junction, vehicles turning to the nearside are separated from crossing cyclists and pedestrians by a buffer, providing increased reaction times and visibility. Drivers looking to turn to the nearside have better visibility of cyclists and pedestrians as they can look to the side for conflicts instead of over their shoulders. At unsignalizedunsignalised intersections, it is practice to have one car length of space between the cycleway and roadway, so that cars exiting the minor street have an area to pull forward and wait for a gap in traffic, without becoming distracted by potential simultaneous conflicts along the cyclepath.
[[File:13-06-27-rotterdam-by-RalfR-25.jpg|thumb|A protected intersection in [[Rotterdam]] in the [[Netherlands]]. A safe way to cross the road on a [[bicycle]].]]
==History==
[[File:Groningen_Grote_Markt_1975_Museum_Exhibit.jpg|thumb|A museum exhibit about the Groningen Grote Markt shows a post-WWII bike lane that forced cyclists to merge with motorists. This design was eventually removed.]]
With the popularity of the bicycle, the Dutch began constructing separated cycle tracks as early as the late 1800s.<ref>{{Cite book|last=|first=|title=The Spectator|publisher=F.C. Westley|year=1898|isbn=|volume=18|url=https://www.google.com/books/edition/The_Spectator/23A_AQAAIAAJ?hl=en&gbpv=1&dq=The+Dutch+are+the+representatives+of+the+beavers+among+men.+On+the+route+from+the+Hague+to+Scheveningen,+for+instance,+there+lie+parallel+to+each+other+a+carriage+road,+a+canal,+a+bicycle+track,+a+light+railway,+side-paths+regularly+constructed&pg=RA1-PA980&printsec=frontcover|pages=980}}</ref> The separation of road users into neatly defined right-of-ways may be linked to Dutch culture in general, which values cleanness and organizationorganisation.<ref>{{Cite journal|last1=Bavel|first1=Bas van|last2=Gelderblom|first2=Oscar|date=2009-11-01|title=The Economic Origins of Cleanliness in the Dutch Golden Age|url=https://academic.oup.com/past/article/205/1/41/1454281|journal=Past & Present|language=en|volume=205|issue=1|pages=41–69|doi=10.1093/pastj/gtp041|pmid=22454968|issn=0031-2746}}</ref> The country's infrastructure was left in ruins by [[World War II]], and some cities like Rotterdam had to be completely rebuilt.<ref>{{Cite web|title=Post-War Reconstruction|url=https://wederopbouwrotterdam.nl/en/articles/post-war-reconstruction|access-date=2021-02-14|website=wederopbouwrotterdam.nl|language=en}}</ref> This presented the opportunity to create infrastructure more in line with the "modern" way. From the 1940s to the 70s, streets were built following a new design philosophy that attempted to integrate cyclists with vehicle traffic.<ref>{{Cite web|last=Peters|first=Adele|date=2015-11-03|title=These Historical Photos Show How Amsterdam Turned Itself Into A Bike Rider's Paradise|url=https://www.fastcompany.com/3052699/these-historical-photos-show-how-amsterdam-turned-itself-into-a-bike-riders-paradise|access-date=2021-02-14|website=Fast Company|language=en-US}}</ref> After three decades, these designs proved to be largely a failure, with the number of kilometers cycled falling by 65% and the per-km rate of cyclists being killed increasing 174%.<ref>{{Cite web|last=Pucher & Buehler|date=October 2007|title=Making Cycling Irresistible: Lessons from The Netherlands, Denmark and Germany|url=https://www.engr.scu.edu/~emaurer/bike/docs/PUCHERMakingCyclingIrresistibleJune2008.pdf|url-status=live|archive-url=|archive-date=|access-date=|website=|publisher=Transport Reviews|volume=28 No. 4, 495–528}}</ref>
In the 1970s, road traffic and urban quality of life began to be seen as a significant issue in Dutch city politics. This, combined with other political headwinds related to party reorganizationreorganisation, the decline of national religious [[Pillarisation|pillars]], and opposition to the [[Vietnam War]] propelled left wing political parties to office in many city governments. In [[Groningen]], a northern Dutch city with one of the highest bike mode shares, the left wing party put forth a new circulation plan which again prioritizedprioritised bicycle traffic and moved away from the notion of designing for bicyclists to act like motor vehicle operators.<ref>{{Cite web|last=Shinji|first=Tsubohara|date=2007|title=The effect and modification of the Traffic Circulation Plan (VCP) - traffic planning in Groningen in the 1980s|url=https://www.rug.nl/research/portal/files/14433101/317.pdf|url-status=live|archive-url=|archive-date=|access-date=|website=University of Groningen}}</ref> As the nation again began to desire separated bike infrastructure, the protected intersection rose to prominence as an engineering solution for optimizing sightlines. It joined other Dutch innovations in traffic calming and bike design, like the [[woonerf]], and the bicycle street (fietsstraat), a variant of which exists in North America (see [[bicycle boulevard]]). Today, the Netherlands is widely considered the world's premier country for cycling, with more than 25% of all trips made by bike.<ref>{{Cite web|last=|first=|date=2008|title=Cycling Facts|url=https://www.government.nl/binaries/government/documents/reports/2018/04/01/cycling-facts-2018/Cycling+facts+2018.pdf|url-status=live|archive-url=|archive-date=|access-date=|website=Kim Statistics Netherlands}}</ref> It has reported a significantly lower cyclist fatality rate following the return to separated infrastructure. In the US, 58% of bicycle crashes involving injury, and 40% of crashes involving death occurred at intersections.<ref>{{Cite web|title=Bicycle Safety Guide and Countermeasure Selection System|url=http://www.pedbikesafe.org/bikesafe/guide_statistics.cfm|access-date=2021-02-14|website=www.pedbikesafe.org}}</ref> In 1972, [[UCLA]] published a report demonstrating awareness in the US of the protected intersection design.<ref>{{Cite report|title=Lessons Learned: The Evolution of the Protected Intersection|publisher=Alta Planning & Design|year=2015}}</ref>
The protected intersection is only one of several treatments for addressing motorist-cyclist conflicts. While used in much of the Netherlands, including Amsterdam, local road authorities in other parts of the country do not use the classic protected intersection with middle islands, preferring to have cyclists move during a completely separated all directions green phase.<ref>{{Cite web|last=Dutch|first=Bicycle|date=2016-06-20|title=Traffic lights in 's-Hertogenbosch; an interview|url=https://bicycledutch.wordpress.com/2016/06/21/traffic-lights-in-s-hertogenbosch-an-interview/|access-date=2021-02-14|website=BICYCLE DUTCH|language=en}}</ref> Other options for reducing bike accidents at intersections, depending on context, include the use of bridges and tunnels, and planning or reconfiguring the neighborhood street/path system so that major amenities and schools can be reached without needing to travel along busy roads.
[[File:13-06-27-rotterdam-by-RalfR-27.jpg|thumb|The protection of the vulnerable cyclists with a protected junction with bicycle traffic lights.]]
In terms of optimal spacing between the path and motorist lanes, it is generally practice to use 2–5 meters at signalizedsignalised crossings and one car length >5m at unsignalizedunsignalised intersections. Providing more buffer space allows vehicles, particularly those turning out of smaller roads, to queue in the waiting area. On the other hand, larger buffers could place the cyclist at a less optimal viewing point from the mainline, and delay the signal operation due to longer distances necessitating slightly longer bicycle signal yellow and all red clearance intervals. The exact optimal distance has been the subject of several studies.<ref>{{Cite journal|last=Schepers|first=Paul|date=2011|title=Road factors and bicycle–motor vehicle crashes at unsignalizedunsignalised priority intersections|url=https://doi.org/10.1016/j.aap.2010.11.005|journal=Accident Analysis and Prevention|volume=43|issue=3|pages=853–861|doi=10.1016/j.aap.2010.11.005|pmid=21376876|via=}}</ref><ref>{{Cite journal|last1=Richter|first1=Thomas|last2=Sachs|first2=Janina|date=2017-01-01|title=Turning accidents between cars and trucks and cyclists driving straight ahead|journal=Transportation Research Procedia|series=World Conference on Transport Research - WCTR 2016 Shanghai. 10–15 July 2016|language=en|volume=25|pages=1946–1954|doi=10.1016/j.trpro.2017.05.219|issn=2352-1465|doi-access=free}}</ref>
===Singalised junctions===
This protected intersection design features a number of common elements that optimise safety:
* A corner refuge island with a reduced turning radius
**A reduced radius could increase difficulties to turn for larger vehicles (trucks and busses), so in some cases, mountable islands have been used, similarly to the truck mountable aprons which surround the centercentre island of roundabouts.
* A setback crossing for pedestrians and cyclists, preferably 5 meters (16.5 ft) at signalised junctions
* A forward stop line, which allows cyclists to stop for a [[traffic light]] well ahead of motor traffic who must stop behind the crosswalk, therefore placing bicycles in better view of a vehicle turning to the nearside.
=== US Design Guide Controversy ===
In 2011, the primary North American planning organizationorganisation NACTO released new design guidelines which claimed to use international best practices while omitting Dutch best practices. This sparked controversy, especially after ambassador of Dutch bicycle infrastructure Mark Wagenbuur criticizedcriticised NACTO for doing so in a prominent trade blog.<ref>{{cite web|url=http://www.aviewfromthecyclepath.com/2011/04/state-of-art-bikeway-design-or-is-it.html |title= blog post: State of art bikeway design, or is it? |publisher=A view from the cycle path| date = 7 April 2011}}</ref> Three years after the furor, Nick Falbo, then part of Alta Planning + Design, a firm behind the NACTO designs, published ‘protectedintersection.com’, which integrated more European design concepts.<ref>{{cite web|url=http://www.protectedintersection.com|title=Protected Intersection|publisher=Nick Falbo| date = February 2014 |access-date=8 January 2015}}</ref>
In 2015, Alta Planning + Design published schematics and some realisations of "protected intersections" in the US and Canada closer to Dutch practice.<ref name="PI evolution">{{cite web|url=https://altaplanning.com/wp-content/uploads/Evolution-of-the-Protected-Intersection_ALTA-2015.pdf | title= Evolution of the Protected Intersection |publisher= Alta planning+design| date = December 2015}}</ref> Later in the year, the [[Massachusetts Department of Transportation]] released their Separated Bike Lane Planning and Design Guide, which includes extensive discussion of protected intersections, and was used as a pilot for the upcoming [[American Association of State Highway and Transportation Officials|AASHTO]] Bike Guide.<ref>{{Cite web|title=AASHTO Guide for the Development of Bicycle Facilities, 2020|url=https://tooledesign.com/project/update-to-the-aashto-guide-for-the-design-of-bicycle-facilities-2019/|access-date=2021-02-13|website=Toole Design|language=en-US}}</ref> In 2019, NACTO, whose original Urban Bikeways Design guide generated the controversy, released "Don't Give Up at the Intersection", which encourages protected intersections as an alternative to bike lane drops.
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